Question

which one of the molecule is not tri atomic

Answer 1

Answer: H2O, CO2 (pictured) and HCN.

Explanation:

Triatomic molecules are molecules composed of three atoms, of either the same or different chemical elements.

Answer 2

For example in a molecule of ozone, 3 atoms of Oxygen exist together as one species and hence it is a tri-atomic with the formula 0³